Fix false return value in findPackage, fixes #10622

src/Composer/Repository/ComposerRepository.php

@@ -208,9 +208,13 @@ class ComposerRepository extends ArrayRepository implements ConfigurableReposito
 
             $packages = $this->loadAsyncPackages(array($name => $constraint));
 
+            if (count($packages['packages']) > 0) {
                 return reset($packages['packages']);
             }
 
+            return null;
+        }
+
         if ($hasProviders) {
             foreach ($this->getProviderNames() as $providerName) {
                 if ($name === $providerName) {